Multiposition liquid fuel burner grille



y 1951 E. H. HAUGEN 2,552,550

HULTIPOSITION LIQUID FUEL BURNER GRILLE Filed Oct. 24, 1946 2 Sheets-Sheet 1 Li 3 2 .2: III 25 22 4 g 24 I8 1 'E I: F 5 T T :1 T I 1 I l lllllll ---E l w l I I 6 I g i I l w I j l234567 89l0|ll2l3l4 TIME-MINUTES AFTER STARTING IN VEN TOR.

F Edmond H. Hougen BY WW ohorneys Patented May 15, 1951 MULTIPOSITION LIQUID FUEL BURNER GRILLE Edmond H. Haugen, Detroit, Mich, assignor to The Timken-Detroit Axle Company, Detroit, Mich., a corporation of Ohio Application October 24, 1946, Serial No. 705,460

2 Claims.

This invention relates generally to fluid fuel burners and more particularly to a means for controlling the mixing of fuel oil and air in a rotary wall flame type oil burner to achieve a more efiicient combustion of the fuel. It is more particularl concerned with improved devices commoniy known as grilles and shown in John A. Wilson Patent No. 2,094,764 and Frank 0. Cole Patent 2,104,691.

Due to the fact that oil refineries are constantly searching for new methods and processes to obtain more and better products from their crude oils, a number of refining processes which give varied physical and chemical properties to the fuel oils produced therefrom have been practiced. The first widely used refining method is a distilling process which produces what is known as straight run fuel oils. These fuel oils have favorable characteristics in that they readily 7 amount of gasoline could be produced from certain distilled crude oil products by heating them to relativel high temperatures under relatively high pressures in a process known as thermal cracking, and the residue was available for fuel oil. The residual fuel oils so produced, as compared to straight run fuels, contain a higher proportion of carbon due to the fact that in the refining process hydrogen was removed from certain hydrocarbon molecules of the fuel oil to go into the production of gasoline. Due to this excess of carbon, thermally cracked fuel oils when used in the rotary wall flame type burners generally tend to deposit a ring of hard carbon about the periphery of the impact wall of the flame rim. Therefore, to efficiently use these fuels, the flame rim must be kept at a relatively high temperature to prevent formation of an undesirable amount of hard carbon deposit.

In recent years the urgent demand for increased amounts of high octane gasoline has led to the use of catalytic cracking wherein a cata lytic agent is used in the distillation of the crude oil product to produce a high octane gasoline along with a residual fuel oil. Fuel oils resulting from this method contain large proportions of carbon similar to those resulting from the thermal cracking method, but have different combustion characteristics in that they tend to burn with a 2 fuel oil. This is due to the fact that the excess of carbon in the oil tends to slow the burning of the fuel and forms a soft fluffy carbon compound that clings to the grilles and the combustion chamber walls.

It has been proven by laboratory tests that these fuel oils maybe efficiently burned only if they are very thoroughly mixed with air in the early stages of the combustion process. I have also noted that when using catalytically refined oils the flame rim temperature must be kept somewhat lower than when burning thermally cracked oils to avoid premature combustion.

As catalytically cracked fuel oils are now becoming more extensively marketed, it can readil be seen that the eflicient utilization of such fuels for heating purposes presents a problem requiring solution.

It is therefore the primary object of this invention to provide an oil burner that will burn fuel oils having various combustion characteristics with substantially equal efiiciency.

A further object of this invention is to provide means in a rotary wall flame type oil burner for maintaining a comparatively low flame rim temperature and for mixing fuel oil vapors and air in such proportions that catalytically refined fuels can be efficiently burned with optimum heat transfer.

A still further object of this invention is to provide a rotary wall flame type oil burner having means for controlling and varying the fuel and air mixing functions of the burner unit.

A more particular object of the invention resides in an improved grille mounting whereby a grille may be mounted in any one of several elevations to control the flow of atomized fuel and air and the intermixing thereof in such a manner as to cause the said burner to have a different mixing characteristic for each of the several elevations of the said grille.

Still another object of this invention is to provide means in a wall flame rotary type oil burner for controlling and varying the fuel and air mixing qualities of the burner unit while at the same time controlling and varying the flame rim temperature.

These and other objects will become apparent as the specification continues in connection with the annexed drawings wherein:

Figure 1 is a fragmentary view of a rotary type wall flame oil burner partially in cross-section and provided with a three-position grille which is the preferred embodiment of this invention;

Figure 2 is a graph illustrating how the temof wall It.

perature of the flame rim is changed as the posttions of the grille are changed;

Figure 3 is a perspective view showing the three-position grille of a preferred embodiment of this invention;

Figure 4 is a view of a sheet metal blank from which one of the grille supports of Figure 3 is made;

Figure 5 is a view of a grille mounted in its low position on the flame rim with its channels in the upwardly open position;

Figure 6 is a View of a grille mounted on the flame rim with its channels in a downwardly open position; and

Figure '7 is a view of a grille mounted in its high position on the flame rim with its channels in the upwardly open position.

The specification continues with reference t the drawings wherein like numerals designate like parts throughout the several figures.

A boiler type furnace 2 is provided with a rotary wall flame type oil burner assembly generally indicated at 4 which is centrally mounted in a ceramic hearth 6 which closes the lower portion of the combustion chamber of the furnace. Oil burner 4 comprises a motor 3 which drives a fan l9, and rotates a distributing head IE to which oil is supplied from a convenient source and is flung outwardly in droplets against an annular sheet metal flame rim 14 by centrifugal force. Flame rim I4 as will appear is an endless carbureting member that may be made segmentally or in one piece as desired.

Flame rim i4 is a continuous sheet steel or other suitable metal trough about the periphery of the combustion chamber having a relatively low vertical wall it for deflecting a disc-like blast of air from fan :0 against the somewhat higher vertical fuel impact wall l3 disposed rearwardly An igniter assembly 2E3 positioned close to the inner periphery of flame rim M is provided with an electrode 22 which terminates close to metal impact wall E8 in such a manner as to provide a spark gap therebetween.

Supported on top of rear impact wall It is a series of individual grilles 25 (see Figure 3) thereby forming a grille assembly 24 about the entire periphery of the flame rim. Grilles 25 are preferably made of sheet steel or other like metal having a high heat resistance and high thermal conductivity. These grilles are substantially of the same construction as the grille of the Cole Patent 2,104,691 and are provided with a plurality of channels 28 and alternating openings 29 between the channels. Each grille is therefore a shallow rectangular box-like frame having flat side walls 3! closing the ends of the channels 23 and apertures 29, and flat end Walls 33 comprising the sides of end channels 28.

Secured to the middle of each end Wall 33, preferably as by welding, is a grille end support or mounting bracket 30 which in the preferred embodiment is made by performing certain cutting and bending operations on a blank of flat sheet metal such as steel having high heat re- 'sistance and high thermal conductivity. Figure 4 illustrates a blank of one of the supports after cutting but before bending along the dotted lines which will form it into final shape.

When in its completed form, each support 39 is secured to grille 25 in such a manner as to place integral spring retainer fingers 32 and 34 beneath the bottom of the end channels and spring retainer finger 36 above the open top of said channels and is provided with a flat body section 38 4 extending above and below the grille and welded to side walls 33. Convergently inclined edges 4!! and 42 of body section 38 serve as bearing faces in cooperation with spring fingers 32 and 36 respectively.

Retainer fingers 32 and 36 are bent inwardly normal to body section 38 and then bent along their outer portions to following the slope of edges 40 and 42 respectively and are spaced from said edges a distance approximately equal to the thickness of impact wall l8. Retainer finger 3 is located closer to adjacent channels 23 than is finger 32 and is bent inwardly normal to section 38 and then bent along its outer portion substantially parallel to the slope of finger 32 in such a manner that the parallel surfaces of the said fingers are spaced apart a distance approximately equal to the impact wall thickness to provide a socket as illustrated in Figure 5.

Each grille 25 therefore is provided with three sets of spring socket pairs, two sets being located on the same side of the grille as the bottom of channels 23 and the other set being located on the opposite side. Each set is designed to support grille 25 at substantially the same angle when clipped onto wall l8, the grilles being so short that the curvature of wall [8 beneath them is not important. The sockets formed by fingers 3B and edge 42 support the grille at the same angle and the same height as the sockets formed by fingers 32 and 34 as illustrated in Figures 5 and 6, but with the channels reversed. The sockets formed by fingers 32 and edges 49 support the grille at a higher level than these other. two positions as illustrated in Figure 7 and this is an important feature of the invention.

In operation, rotating distributing head [2 provides impingement of small unatomized oil droplets against impact wall l8 and they are at first atomized and ignited by a spark from igniter 29 to burn within the trough of flame rim M. The oil droplets distributed by head !2 have a trajectory at a higher level than the air stream from fan I9 as disclosed in said Cole patent. The temperature of the flame rim increases due to the oil burning in the trough, and the atomized droplets of oil soon become vaporized when Wall l8 reaches a sufficiently high temperature. After leaving impact wall Hi the vaporized oil is upwardly deflected toward and through grilles 25 by the disclike blast of air from fan It. Between the flame rim and the grilles, the air and vaporized oil are admixed and they are further mixedand uniformly distributed about the periphery of the combustion chamber. The combustible mixture now burns above the grilles as can be noted by watching the burner in operation. Heat from the grilles radiated back to flame rim l4 helps to keep the flame rim at the relatively high temperature necessary to insure vaporization of the oil droplets.

The main purpose of the grilles is to control and effect further mixing of the fuel oil vapor and the air stream and to' determine the location of the flame relative to the flame rim since a mixture of fuel oil vapor and air will not ignite until a certain critical mixture capable of supporting combustion is reached. If no grilles are present, this combustible mixture stage is not time to form. ,The'relationship of the flame rim to the location where combustion takes place controls" the operating temperature of the flame rim and it is desirable to maintain the flame rim temperature as low as possible while efficiently burning'the fuel. Inasmuch as the fuel oil isya p r-ized upon impact against the hot flame rim and the air is deflected against the flame rim, the temperature of the flame rim is in turn a governing factor in determining the temperature of the fuel oil vapor and air at the time the critical mixture necessary for combustion is reached.

As before stated, the grilles of this invention are capable of being mounted in any one of three operative positions, each of which will produce different burning conditions and cause the flame rim to have a different operative temperature.

When the grilles are supported on the flame rim by retainer fingers 32 and 34, as in Figure 5, channels 28 are held in their upwardly open position which causes the grilles to have certain mixing qualities and determine the location of formation of the combustible mixture of fuel oil vapor and air. This is the position wherein each grille exerts the least mixing action as the channels 28 simply deflect the mixture through the grille. This grille position is widely used for straight run fuel oils since it produces efiicient carbon free burning and optimum heat exchange with the boiler. This grille position also permite the flame rim to remain at a relatively low operating temperature which is less destructive to the flame rim.

When burning poorer grades of thermally cracked fuel oils which would cause hard carbon deposits to appear upon the flame rim if the above position was maintained, the grilles are inverted and supported on the flame rim by retainer fingers 3'6 and edges 42, as illustrated in Figure 6, placing the channels 28 of the grilles in a downwardly open position and causing the grilles to have more pronounced mixing qualities. The channels trap a portion of the mixing fuel oil vapor and air that is deflected against them and thus retard passage through the grilles and in general cause the critical mixture necessary for combustion to take place closer to the flame rim than in Figure 5 thereby causing the flame rim to operate at a higher temperature than the previously described grille position. This higher temperature is necessary to burn off the hard carbon deposits on the flame rim and to prevent the re-occurring of these carbon deposits.

The above described two grille positions of Figures 5 and 6, wherein the grilles are at substantially the same height above the flame rim, are disclosed in Cole Patent 2,104,691 to which reference is made for further detail.

The grilles, when supported on the flame rim by retainer fingers 32 .and edges 48, as illustrated in Figure '7, are held at a greater vertical distance above the flame rim than in the two previously described positions, which therefore provides more distance and space for mixing the fuel oil vapor and air before reaching the grilles. The greater height of the grille above the flame rim in this third position results in emcient burning of catalytically cracked oil and in the flame rim having lower operative temperature than that corresponding to the grille position of Figure 6.

Figure 2 illustrates graphically the results of practical laboratory tests made to determine the relative effects of each of the three abovedescribed grille positions upon the flame rim tembecause of its relatively high flame rim temperature prevents deposition of hard carbon compounds upon the flame rim. Curve Z illustrates the results of the grille position of Figure 5 which is used in standard field practice for the burning of straight run fuel oils and better grades of thermally cracked fuel oils.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects, as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A sheet metal grille adapted for multiposition attachment to the sheet metal flame rim of a wall flame burner assembly comprising a shallow frame having side members interconnected by spaced transverse troughs and two end members, each of said end members being formed with a plurality of outwardly open slots and at least one side of each slot being a spring metal finger integral with the end member, a pair of said slots in the respective end members being aligned to form a socket for angularly mounting the grille upon the flame rim in a first position, a second pair of said slots in the respective end members on the opposite side of the frame from said first pair being aligned to form a socket for angularly mounting said grille upon the flame rim in a second position with the troughs reversed from said first position but with said frame at substantially the same vertical height from said flame rim in both said first and second positions, and a third pair of said slots being aligned to form a socket for angularly mounting said grille on said flame rim in a third position in which the frame is disposed at a greater height above the flame rim than in either of said first and second positions, said position being adapted for efficiently burning different grades of combustible oil, and said slots for providing the second position socket having both sides defined by spring metal fingers, one of which is the spring metal finger that forms the side of the adjacent slot providing the third position socket.

2. A sheet metal grille adapted for multiposition attachment to the sheet metal flame rim of a wall flame burner assembly comprising a shallow frame having side members interconnected by a serie of spaced transverse members and two end members, each of said end members being formed with at least two outwardly open slots and at least one side of each slot being a spring metal finger integral with the associated end member, one pair of slots in the respective end members being aligned to form a ocket for angularly mounting the grille upon the flame rim in a, first position and a, second pair of said slots in the respective end members being" aligned to form a socket for angularly mounting the grille upon the flame rim in a second position at a higher level than said first position, said slots 5 for providing the first position socket having both sides defined by spring metal fingers, one of which is the spring metal finger that forms the side of the slot providing the second position socket.

EDMOND H. HAUGEN.

The following refer nces are of record in the 8 REFERENCES CITED file of this patent:

UNITED STATES PATENTS Number Name Date Cole Jan. 4, 1938 

